Valves and valve actuation – Permanent or constantly energized magnet actuator
Reexamination Certificate
1998-04-21
2001-01-30
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Permanent or constantly energized magnet actuator
C251S129080, C335S229000
Reexamination Certificate
active
06179268
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a proportional variable force solenoid operated valve that controls fluid pressure in response to electrical current applied to a valve solenoid and, more particularly, to a proportional variable force solenoid operated valve having permanent magnet segments disposed in pockets in a coil bobbin.
BACKGROUND OF THE INVENTION
A proportional variable force solenoid control valve that is relative low in cost to manufacture and compact in size while maintaining substantially linear proportional fluid control is described in the Najmolhoda U.S. Pat. No. 4,988,074 issued Jan. 29, 1991, of common assignee herewith. The patented proportional variable force solenoid control valve comprises an outer steel solenoid housing and an aluminum valve member housing joined together mechanically such as by tabs on the steel solenoid housing being crimped about regions of the aluminum valve member housing.
The proportional variable force control valve includes a ferromagnetic (e.g. steel) armature suspended by low spring rate springs at opposite ends of the armature within the bore hole of a coreless solenoid bobbin for reciprocable movement between positions corresponding to a closed valve position and fully open valve position in response to applied electrical current to an electromagetic coil. The position of the armature is controlled by balancing the variable force of an electromagnetic field of an electromagnetic coil and the force of the magnetic field of a one-piece permanent ring magnet against the force of a compression coil spring which biases the valve toward the closed position of the valve. The electromagnetic coil, bobbin and armature reside in the steel solenoid housing in a manner that the steel housing provides a concentration of flux of the electromagnetic field at the armature. The permanent ring magnet is heat staked in position on the coil bobbin. The fluid control valve on the end of the armature moves relative to a valve seat disposed in the aluminum valve housing to communicate a fluid inlet to fluid exhaust ports so as to regulate fluid pressure at fluid control ports in a manner proportional to the magnitude of applied electrical current.
A commercially manufactured version of the aforementioned patented proportional variable force solenoid fluid control valve has been modified to include a stainless steel ball valve and a separate stainless steel valve seat insert pressed in the nozzle. The ball valve is captured in a stainless steel cage between the valve seat and a rod-like, cylindrical shaped steel armature that moves relative to the valve seat in a manner proportional to the magnitude of electrical current applied to the electromagnetic coil. As the armature moves relative to the valve seat to actuate the valve, the ball valve is caused to follow the end of the armature by virtue of fluid pressure in the valve member housing and confinement in the ball valve cage in the bobbin. The fluid inlet is communicated to fluid exhaust ports by opening of the ball valve so as to regulate fluid pressure at fluid control ports in a manner proportional to the magnitude of electrical current applied to the coil.
A spool valve is disposed in the valve member housing for providing a two stage, high flow capability wherein pressurized fluid supplied to the inlet port initially is directed to bypass the control ports and flows to an end of the spool valve to move it from a zero fluid flow spool position to a maximum fluid flow spool position relative to the control ports as determined by the cracking pressure preset for the ball valve by adjustment of the coil spring force. Thereafter, a second stage of operation involves controlling the fluid flow through the control ports by moving the spool valve between minimum and maximum flow spool positions in a manner proportional to the magnitude of electrical current to the coil. Such proportional variable force solenoid control valves commercially manufactured to-date are operably mounted to a cast aluminum transmission body or case by a clamp plate, bolt, or both engaging an outer nozzle groove.
The Najmolhoda U.S. Pat. No. 5,611,370 issued Mar. 18, 1997, also describes a proportional variable force solenoid control valve that includes a substantially non-magnetic common housing for the solenoid and control valve, simplfying valve manufacture and construction while maintaining substantially linear proportional fluid pressure control.
An object of the present invention is to provide a proportional variable force solenoid fluid control valve having multiple permanent magnet segments received in pockets of the coil bobbin to simplify construction and lower cost of the control valve.
SUMMARY OF THE INVENTION
The present invention provides a proportional variable force solenoid fluid control valve for controlling the pressure of a pressurized fluid in a fluid control system in proportion to the current level of an electrical input signal. In one embodiment of the present invention, the proportional variable force solenoid fluid control valve comprises an armature in engagement with a fluid pressure control valve and movable in response to electrical current applied to a solenoid disposed on a coil bobbin in a solenoid housing and means for biasing the armature in a direction to establish a valve fluid pressure response to current level supplied to the solenoid (i.e. fluid pressure versus solenoid current). A plurality of axially magnetized permanent magnet segments each having an inner arcuate magnet surface facing the armature are provided to collectively provide a permanent magnetic field that cooperates with the electromagnetic field of the energized coil to move the armature. The permanent magnet segments are disposed in a circular array about the periphery of the armature in respective circumferentially spaced apart, axially extending pockets of the coil bobbin in a common transverse plane relative to the longitudinal axis of movement of the armature. The magnet segments are selected in number and arcuate surface extent to collectively encompass or overlie less than 100% of the peripheral surface of the armature when viewed in cross-section transverse to the longitudinal axis. Preferably, inner arcuate surfaces of the permanent magnet segments collectively encompass at least about 67%, preferably about 70% to about 80%, of the peripheral surface of the armature when viewed in transverse cross-section.
In one particular embodiment of the present invention, each permanent magnet segment includes an inner arcuate surface facing the armature and an outer arcuate surface to form a generally C-shaped magent segment. Each magnet segment includes axial side faces with each segment axially magnetized between the side faces and radially extending end faces that are cicumferentially spaced from the end faces of an adjacent magnet segment. When viewed in transverse cross-section, the end faces of the permanent magnet segment are disposed in radial planes that intersect the center of a cylindrical armature.
The coil bobbin of an embodiment of the invention includes respective axially extending pockets to receive each permanent magnet segment with the axial side faces oriented generally perpendicular to the longitudinal axis of movement of the armature. Each pocket is defined by an inner arcuate opening, an outer arcuate wall and radially extending end walls to this end. Each pocket includes an open outer end through which a respective magnet segment is inserted into the pocket and an inner end closed by an axial pocket wall extending generally perpendicualr to the longiudinal axis. Each magnet segment is confined in its own pocket and separated from adjacent magnet segments by the end walls of the pocket and from the armature by the inner arcuate opening of the pocket. Each magnet segment preferably is frictionally confined in each pocket by, for example, the radially extending end faces of the magnet segment frictionally engaging axially extending locating posts provided in each pocket proximate
Bastianelli John
Saturn Electronics & Engineering, Inc.
Shaver Kevin
LandOfFree
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